"I can even see color with it"...is this supposed to be odd or something?

Yes, because only the cones [wikipedia.org] in the center of your eye are capable of perceiving color (the rods on the outside perceive only black and white.) Your brain senses everything in the periphery of your vision in black and white, but "fills in" best-guess colors from what your cones perceive directly in front of you.

I remember that from a psychology lecture only because a fellow classmate, like the parent poster, couldn't believe the color in his peripheral vision was an illusion. So, the professor drew an "X" in the middle of the chalkboard and asked him to stare at it without looking away. He then held up a colored note card directly in front of the "X" and asked him to name the color. (Of course, he named it correctly.)

The professor held up another note card, a bit further away from the X, and asked him to say what color that card was. And then he held up the next card, a bit further away from the X than the last one. And he kept holding the cards further and further towards the edge of his field of vision.

After about the fifth card, the kid was convinced that any card the professor held up was either a shade of gray, or the same color as the chalkboard. Once the note cards were in his peripheral vision, he couldn't tell what color they were, and couldn't tell that he couldn't tell what color they were. Great professor.

Uh, did you read the Wikipedia link you posted? "Cone cells are densely packed in the fovea, but gradually become sparser towards the periphery of the retina." They aren't located only in the fovea, but all across the retina. They're merely more densely packed in the fovea than towards the edge. What most likely happened to your classmate is cone bleaching [ucsd.edu]: the longer you stare at a particular image, the more the particular cones bleach their photoreceptors, and the harder it is to figure out the correct color. Depending on what color the chalkboard was, it's quite possible he simply had stared at it for too long.

The retina still perceives color at the edges, it just does so less effectively than if you focus on the center.

wait, is this really all they're tryin to prove? I'll admit, I pulled a non-RTFA, but shit, I've known for years that peripheral vision was not great at discerning detail. I've done degree tests, and while I can detect items slightly beyond the 180 degree plane, I have no clue what they are. If that's their point, this is first-year psychology shit. The center of human vision is accurate yet less sensitive to movement, and the peripherals are vice versa. That appears to be the way things should be, an objec

Except that's not what they tried to show. The site demonstrates that when objects are moving relative to your field of view you become less able to discern changes to the objects themselves, whether it's a change in coloration, size or shape. This is not interesting because your peripheral vision is bad - when the objects are stationary it's easy to tell that they are changing - it's interesting because it's a property of human vision that apparently wasn't known yet.

In fact, just try to focus on one of the dots in the videos. Even if you know it's going to move, you know it's going to keep changing color and the dot is in your center of view you still might fall to the illusion (not to mention that other dots nearby also seem to be unchanging even though they're right next to the one you're trying to follow).

It's not about central vs. peripheral sight, it's about how motion and the perception of change interact.

When I debated getting an advanced degree in psychology, this is what I would have done my thesis on. 20 years ago. Though I was going to work it as predisposing a person to declare an unclear object as something, then when the image becomes more clear, how long after it's clear from a still image until they can identify it's not what they thought it was. The point being that if you are driving along and see a bag blowing and mistakenly identify it as a squirrel, it will take longer to identify it as a b

I don't normally bother to reply to these sort of posts, but: why on Earth did you think this comment was a good idea? You, by your own admission, didn't bother to read the article and clearly didn't understand what was being tested from the summary. What makes you feel qualified to criticise? Are you really so arrogant that you feel comfortable condemning something as "first year psychology shit" when you don't even know what it is, you haven't bothered to find out what's being studied, and the researchers

I think this was fairly well known (at least intuitively) by magicians. As long as you keep your hands moving, people can't tell what you are doing with them.

Sleights of Mind: What the Neuroscience of Magic Reveals about Our Everyday Deceptions by Stephen L. Macknick and Susana Martinez-Conde.

I saw this book at the Bucktown branch of the Chicago Public Library earlier today in the "New Non-fiction" section. I took it out but haven't had the chance to crack it yet. It looks like it speaks directly to your point.

This is from the blurb:

Stephen Macknik and Susana Martinez-Conde, the founders of the exciting new discipline of neuromagic, have convinced some of the world's greatest magicians to allow scientists to study their techniques for tricking the brain. This book is the result of the authors' yearlong, world-wide exploration of magic and how its principles apply to our behavior. Magic tricks fool us because humans have hardwired processes of attention and awareness that are hackable—a good magician uses your mind's own intrinsic properties against you in a form of mental jujitsu.

Now magic can reveal how our brains work in everyday situations. For instance, if you've ever bought an expensive item you'd sworn you'd never buy, the salesperson was probably a master at creating the "illusion of choice," a core technique of magic. The implications of neuromagic go beyond illuminating our behavior; early research points to new approaches for everything from the diagnosis of autism to marketing techniques and education. Sleights of Mind makes neuroscience fun and accessible by unveiling the key connections between magic and the mind.

It's actually slightly more complex than that; a Magician's task is to use body language, banter, props, etc to make people see one part of the picture while ignoring another part... and using humans' built in narrative creativity to fill in the hole (which is where you do the tricky stuff) with something from their own mind. Of course, moving your hands in *almost* predictable, common ways tends to fool most people into thinking that's exactly what you're doing.

Our eyes are trained to do a whole lot of quick thinking and estimates before sending the raw data to our brain. This is one of the many reasons why simply hooking a camera up to the optic nerve doesn't quite produce the desired results - though our brains seem to be super-learning computers able to interact with almost any other kind of Input - Output, given enough time for trial and error.

I imagine our Eyes are trained to generalize the colour it sees and focus on the appearance of motion, because thats usually more important and relevant to survival, and our eyes are just like technology: Limited bandwidth.

You might call it a defect, I might think of it as evolutionary design.

That depends on what you call a processor. The eyes do a bit of preprocessing - the raw output of the rods and cones isn't fed directly into the optic nerve; intermediate cells inhibit and excite each other, altering the image in-eye. One example of retinal filtering is how Mach bands [wikipedia.org] are created: Lateral inhibition between the cells causes edges to appear more pronounced than they actually are. The brain is not involved.

(Essentially, the more light one cell receives, the more its neighboring cells are inhibited. At an edge between a light and a dark area, a "light" cell close to the edge will receive less inhibition than entirely bright-surrounded cells due to its "dark" neighbors and thus the light side of the edge will be perceived as brighter. Conversely, the "dark" cells closest to the edge will receive stronger inhibition than other "dark" cells due to their "bright" neighbors, causing that side of the edge to appear darker.)

IAAVN (I am a Visual Neuroscientist). It's a compelling illusion. I have not read the original paper, but will speculate nevertheless in true Slashdot fashion. The change that's perceived before the ring rotates is not so much due to the colors changing -- if you pay close attention -- but something that's called apparent motion. The classic example of apparent motion is the sequencing of lights around a movie marquis -- they appear to move, although the lights themselves are not actually moving. In the same way, the static ring has internal apparent motion as the colors change, because your brain is interpreting, for example, one dot turning yellow next to a dot that was previously yellow, as motion of a yellow dot, even though the underlying dots do not move. While apparent motion can be very strong, it is not the same as true motion.

Then, when the ring starts to rock back and forth, there is a true motion signal that swamps the apparent motion. If you pay attention to a given dot while holding your gaze still fixed at the central white point (not as hard as it sounds), you can clearly still see the colors changing.

So without having read the paper, I reserve some skepticism that they have not actually measured what they think they have. Change is still perceptible, but it would seem that real motion interferes with apparent motion.

I won't disagree with a pro on this, you're probably right that they didn't measure what they thought -- as Feynman pointed out, even with rats, a good experiment is truly difficult to design.

On the other hand, the premise might be believable even if the experiment is flawed. Humans needed to detect motion above all else to survive earlier on in evolution, as something moving might have plans to eat one of us. We can see tiny movements where we can't see diddly staring right at the same thing motionless

I think in this case, when the ring is static, each individual object is a unique entity. Changes matter.

When the ring is in motion, each individual object becomes part of the whole. It is now one ring and we ignore changes occuring to the ring.

This is entirely sensible because when an animal is in motion, we don't care about the muscles rippling, or the feathers ruffling, or the fur shimmering, or the shadows from trees dancing on it. Our survival depends on being able to watch the animal itself as a single unit. So we are hard wired to ignore the micro changes to a single object.

When the ring moves, all the tiny objects join to become a single ring we must track. When it's not moving, we see they are separate objects.

I think the illusion in this is because it's a group of shapes, plus persistence of vision - just like any other animation. My brain tracks the common sizes/colours spinning aroubnd, not original entities.

Thanks for confirming what I said. Like you said, the only way you got busted is someone noticing something had changed from one observation to the next, because you knew how to be patient and move so slowly that no one ever saw you actually move -- am I right?
Real sniping ain't no video game, and anyone who has knows that.
I was a different type of cold warrior -- I worked signals, sources, stuff like that.

The gorilla illusion is not the same. That's an illusion based on the limitations of our attention; it is not a change illusion.

Fair point about reading the paper. I've downloaded and done a quick first read-through. If you look at Figure 1, they show the results for the four different kinds of change they tested, hue, luminance, size, and shape. The first two are more readily interpreted as apparent motion when the changes are slow. Their results show that the first two illusions are more susceptible

Bugger - I'm going to have to do some research! Time for some reading, its almost as though a/. story might become interesting.

Right - I cry foul almost immediatly (I've only watch the first vid):

Its common(ish) knowledge that the visual field is very narrow. The fovea centralis http://en.wikipedia.org/wiki/Fovea_centralis [wikipedia.org] only covers a very small area, and I'd be willing to bet (only a small amount) that causes the apparent lack of movement.

hi jon, i'm one of the authors of the paper. just thought i'd answer your question about the refresh rate. we used laptop screens that ran at 60 Hz, but the demo works even if you keep the dots motionless and lift up the screen and rock it back and forth. (you can try this yourself if you download the video.) the demo also works on a CRT at 120 Hz. so yes, it the refresh rate was considered and controlled for, and it doesn't seem to matter much. the motion in the youtube and vimeo videos are a bit jerky because they were converted to 30 fps.

hi jon, i'm one of the authors of the paper. just thought i'd answer your question about the refresh rate. we used laptop screens that ran at 60 Hz, but the demo works even if you keep the dots motionless and lift up the screen and rock it back and forth. (you can try this yourself if you download the video.) the demo also works on a CRT at 120 Hz. so yes, it the refresh rate was considered and controlled for, and it doesn't seem to matter much. the motion in the youtube and vimeo videos are a bit jerky because they were converted to 30 fps.

Mod this up!!!

Hey Moderators, we have an actual author of one of the discussed stories replying to a direct question in a thread. I think this merits some "+1 Informative" points.

Since you're one of the authors, I thought I'd chime in and share my experience. I'm partially color blind, and if you put certain reds, greens and/or grays next to each other I have a real hard time distinguishing what's what. I'm not sure how much that affected what I perceived when I watched these.

When I watched the first video with the vividly colored dots, and they started moving, I thought "Huh, I don't get it. I see the colors change. What's the big deal?" My wife, who was watching at the same time,

>>we used laptop screens that ran at 60 Hz, but the demo works even if you keep the dots motionless and lift up the screen and rock it back and forth.

You know this doesn't change anything, right?

Think about it from the point of view from the retinal afterimages left on an observer - if the laptop is moving a dot 1 inch/second on its screen, it will leave 60 afterimages, each spaced 1/60th of an inch apart. If you move the laptop instead, the observer will also have 60 afterimages in the second, also 1

The gorilla illusion isn't universal, either - I successfully counted 15 passes AND saw the gorilla (complete with chest-beating) on my first view. I would wager than a not-insignificant percentage of people could do the same. I would even posit that the set of people who are "immune" to the gorilla illusion would intersect somewhat with the set of people who have high skill at rhythm gaming - both require tracking lots of moving objects.

You may have been lucky or you may be gifted - who knows but in this case (ie this discussion) we have two data points - I missed it and you didn't. Now even on/. that is not normally considered proof one way or the other.

I got to the video by following a link that said "gorilla", in the context of a discussion of optical illusions. Of course I saw the gorilla - I was expecting it. (Idea for a follow-up experiment: make a video without a gorilla, and convince people that there is one in there.)

im having trouble seeing this illusion, i kinda understand what im supposed to see but im not getting that response that is described.

Could that be because im a professional gamer, Focusing on competing in Starcraft 2 at this point in time. When massive armies clash and they have to be microed everything is moving around and changing and requires exact placement and control, Could it be that i simply have become immune to this illusion of not noticing when something is moving?

Personally, I didn't see a complete cessation of flashing/pulsating/shapeshifting, although it did seem to slow while the dots were rotating as a unit. I could definitely still sense that the dots were changing independently of the rotation, however.

Though IANAVN, I'm not so sure. Wouldn't that mean that the apparent motion shouldn't be visible during the rocking motion? That seems so in the size-change video (even if it is the least contrasty one), but in the first one there are several groups of dots that have an apparent movement, especially the darker blue "worms". I still see that apparent motion around the donut while they're also moving for real. But most importantly, the shape-changing video doesn't seem to have any apparent motion at all while

Technically, the monitor used to watch the video works by apparent motion as well (i.e. 60 Hz refresh rate). Perhaps the optical illusion of apparent motion doesn't work as well with the second iteration. A good test would be to replicate the illusion with physical objects (not that I RTFA to see if they did this).

There'd be an evolutionary advantage to observing the properties of a moving object, so I'd be surprised if we have a lot of trouble with it. Observing the shockwaves in the fur of a moving

I noticed that when I was looking at the unmoving dots, I saw them as individuals. As they started moving together, I reinterpreted them as a single mass made up of dots. It would be interesting to see if the effect is the same when the dots are moving in different directions and at different speeds.

That's exactly what I found as well. I tried to work out what was going on, and noticed that if I did fix my "peripheral attention" on a particular outer circle as it moved, I could detect its changes, and a little of those adjacent to it.

I think also what is happening is that, when rotation begins, many dots are traversing the *same area* of vision while your eye is keeping very still. So instead of the brain "intentionally silencing" change over motion, another possibility is simply that points are traver

Mod this post up. IANAVN (I am not a Visual Neuroscientist) but I noticed the same thing. If I narrowed the focus to a specific section of the circle, even when it was moving, I could see the color , shading, or shape changes with no problem. I had a hard time focusing on the entire ring at the same time when moving.

Just as an aside, is this really news? Don't most of us recognize from everyday life that it takes more effort to focus on details of moving objects, the faster the objects are moving relati

demonstration of how when the brain receives two different associated inputs and determines one is much more important than the other, how well it focuses you on just the important one.

In a predator-prey situation, prey are usually excellent at spotting movement. It's not surprising that when we see something start to move that's a bit dynamic, (like a tiger running through our view among the grass) how our brain "freezes" the image and allows us to process a more static interpretation of it while we track

For a large part of humanity, being lunched by a sabre toothed donkey has not been much of a worry for a very long time.

So why not couch your argument in terms that are relavent? Have a think and decide how long ago your ancestors would have worried about a tiger (rather than say being nobbled by the local feudal system or disease) and then decide what the "rate" of evolution is.

1) color-blind people don't see in black and white, they lack usually one of several photopigments and lack the ability to distinguish between a few colors that normal people can. red and green for example look the same to someone with RGCB. They can distinguish all the other colors, it's just that those two look identical.

2) sex linked has little to do with evolution in this case. you need one copy of the photopigment DNA to produce the pigment. Women have two X chromoso

Switching something when it is in the middle of fast movement is the basis of all kinds of slight of hand tricks. There's just a certain state where the mind identifies something just as a blurb of overlapping color, rather than anything processed meaningfully, and you can freely swap it with a similar item without any notice. Mix in basic misdirection, and you can fool almost anyone's expectations. It's also why you kind of have to learn to juggle by feel & pattern rather than just sight - because the hand really does have to be faster than the (mind's ability to process information from the) eye to keep up with the pattern.

As a magician, I have known this for years. Dai Vernon, The Professor [wikipedia.org], explains that concept the scientists just discovered as a simplistic beautiful statement, "A larger action covers (or hides) a smaller action."
Science finally catches up to the magicians.. Damn them.:-)

Unfortunately the video player had no indication that it was not loading at all (likely slashdoted), instead just sits static on the first frame. However, it took me about 30 seconds of staring at the static image wondering if my since of perception was so bad I -didn't see anything moving at all-

Turns out it is pretty bad, just not in the way I thought; I recommend going straight to the youtube versions linked on the article.

It's a pretty neat effect, sort of one of those things that become pretty obvious once you see it.

so why would there be a difference between when the things move vs. don't move? there are always a mix of colors and brightnesses.

When you're a monkey moving through the forest, things are passing by as you're moving in and out of pools of light. Your eyes are trying to adjust to it. That's what the test they showed seem to be testing anyway.. the background was changing luminance while multi colored things roamed about.

As a former competitor at the world-level in first person shooters, perhaps my cortex has adapted differently, because when I stare at the dots in the center, I can always tell that the shape or hue or brightness are changing. I can tell when they change and how they change. I can see how in many ways this might be true for 99.99% of the population, but when you spend man-years staring at stationary dots in the center of a screen (crosshair) while "looking around" in-game waiting to notice single-pixel ch

Who only noticed a *diminished* sense of the colors changing? I could still see the colors changing, it just didn't seem to be nearly as much as before the dots started moving. My experience was as follows: 1) Ok, colors changing 2) dots moving and wow the changes stopped! 3) oh wait, no I'm seeing a few changes still....

In true/. style, I watched the video without reading anything else. As I was staring at the colors changing, everything started rotating so I focused on the center dot, wondering what was going to happen next. As I did this, I lost all perception of color changes and only saw the motion. Sooooooo, either I'm not a world class gamer like Trouvist [slashdot.org], or the affect was pretty much as reported by the researchers. I'm gonna go with option b on this one.

No, you aren't the only one. I could also see the illusion initially for a fraction of a second, then I started seeing the hue changing in a subdued manner. Let's set perception of change when still to 100%, that is, 100% of dots in number change and they do so in 100% intensity. In motion, it's about 30% in number and 50% in intensity. In contrast, I was pretty much blind to the size change. This is, in fact, analyzed in the article: it's because it's hard to keep the gaze exactly still. There's a strong r

Nice illusion indeed, and at least partially new. A while back, I combined two different illusions to make a single more effective illusion. I wonder if there's any connection with the one in the news article as they both seem to rely on the movement of peripheral vision confusing other aspects of change in peripheral vision:

Because in a primitive, hostile environment, the main thing is to see the enemy / victim coming. That's one of the reasons why people keep watching anything that moves above static parts. That it also changes color.. well.. big deal. Noticing it moving is much more important.

In the example videos, the changes are not random, they are a pattern that rotates around the group. (Watch the shape change and size change to see it most obviously, but it's there in the color/brightness ones as well.)

So when the group starts rotating, it is actually counter-balancing the individual item change. You're losing sight of the trees for the forest.

Example: a group of people are on a merry-go-round. Each one is holding paper with a symbol on it facing up. They start passing their papers aro

The reef squid has the ability to quickly change colors and patterns on it's body, and seems to signal other squids in this fashion (as well as for camouflage). I wonder if they would be fooled by this illusion or if their neural optics are wired very differently than ours. It would be challenging to try to create an objective test that you could do with them.

I won't necessarily claim to be one here, since anyone can claim anything on the internet. But I wonder how well experienced MTI analysts (http://en.wikipedia.org/wiki/Moving_target_indication) would perform against these videos. Quite literally, it is the job of an MTI analyst to distinguish coherent from non-coherent changes across a vast number of moving dots displaying all sorts of crazy behaviors.

Additionally, I would prefer to see this experiment run under different conditions, such as having the vi

It seems to me that this is a fairly simple illusion: the frequent event is "more interesting" hence the brain focuses on that. Color change in this example is happening slower than rotation hence motion is favored instead of colors.

I suspect that this is an optical illusion triggered because the brain is trying to match items by color and size. When color or size changes, the brain matches the wrong blob (which hasn't changed, or just happens to have changed to what the other one was, or to something closer to what the other one was than the other now is) to the original item.

I'd like to see a video with just the fixation point and one datapoint in the periphery. If we still lose track of shape and color changes then that will be ha

instead of making a video, couldn't they have made a flash thingie, so that you could change the parameters of the illusion too? maybe we could then tell at what rotation speed color change becomes hard to notice.

hi, stupid scientist #1 here. (i'm one of the authors of the paper.) you're right, it would be nice to have a flash app that lets you change the speed of rotation. sadly, i programmed everything in MATLAB and I don't know flash. (and hey, didn't our overlord already pronounce flash dead?) on that note, if anyone knows flash and wants to program this up into an interactive demo, send me a message, i'm sure we could work something out.

but you're in luck, my friend. the demo works even if you pick up the screen and rock it back and forth, and i have a movie (link below) with no motion. you can loop the video and whirl the computer around all you'd like, at various speeds.

The video directs the user to state at a stationary object (and even then it's not hard to notice some progression). If you actually look at the moving objects (you know, like the way people who aren't undergoing the Ludovico Technique normally look at stuff), it's quite easy to notice what's going on.

"people are remarkably bad at noticing when moving objects change in brightness, color, size, or shape"

I think you left out an important qualifier:

people are remarkably bad at noticing when moving objects change in brightness, color, size, or shape IN THEIR PERIPHERAL VISION

If you look directly at any of the moving objects you can see any of them change in brightness, color, size, or shape. Your peripheral vision is not your focus for good reason, and of course its not going to track every single change like at the center of your focus of vision, its not supposed to and is better that it doesn't.

When looking at the video I see all of the color changes, even when the ring is in motion. Then again, I am also one of those who can see the cycle rate of flourescent lights. Perhaps my eyes are hyper sensitive or have a higher bandwidth path to my brain than most people. I was in Vegas in November and saw the David Copperfield show and was in the front row. I was able to see the slight of hand that was being used to swap objects and figure out how he was doing the tricks. Made it somewhat boring for